Method and apparatus for additive manufacturing

ABSTRACT

A method for forming at least one three-dimensional article through successive fusion of parts of a powder bed on a support structure, the method comprising the steps of: providing at least one model of the three-dimensional article, lowering the support structure a predetermined distance and rotating the support structure a predetermined angle in a first direction before applying a first powder layer covering the lowered and rotated support structure, rotating the support structure the predetermined angle in a second direction opposite to the first direction before directing the at least one first energy beam from the at least one first energy beam source at selected locations of the first powder layer, the at least one first energy beam source causing the first powder layer on the stationary support structure which is stationary to fuse in the selected locations according to the model to form first portions of the three-dimensional article.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/565,596, filed on Sep. 29, 2017, the contents of which as arehereby incorporated by reference in their entirety.

BACKGROUND Technical Field

The present invention relates to a method and apparatus for additivemanufacturing of 3-dimensional objects.

Related Art

Freeform fabrication or additive manufacturing is a method for formingthree-dimensional articles through successive fusion of chosen parts ofpowder layers applied to a work plate.

Such an apparatus may comprise a work plate on which thethree-dimensional article is to be formed, a powder dispenser, arrangedto lay down a thin layer of powder on the work plate for the formationof a powder bed, a laser beam source for delivering energy to the powderwhereby fusion of the powder takes place, elements for control of thelaser beam source over the powder bed for the formation of a crosssection of the three-dimensional article through fusion of parts of thepowder bed, and a controlling computer, in which information is storedconcerning consecutive cross sections of the three-dimensional article.A three-dimensional article is formed through consecutive fusions ofconsecutively formed cross sections of powder layers, successively laiddown by the powder dispenser.

FIG. 1 illustrates schematically an additive manufacturing apparatuscomprising a laser source 1 directed by scanning optics 2 such that thebeam 3 defines a 2-dimensional pattern in a thin bed of metal powder 4.Where the laser impinges upon the bed of powder, the powder is fused toform a solid layer 5 bonded to a base plate 6. When the first layer iscompleted, the build plate is indexed down by the elevator mechanism 7.The powder bed is then replenished to the original level by the powderdistributor 8 which scans horizontally so as to scrape powder frompowder supply hopper 9 and deposit a uniform layer above the previouslyscanned layer. The second layer of powder is then scanned so as to fusethe required areas of powder onto the previously fused layer 5. Byrepeating this process, a 3-dimensional article is progressively buildup, being composed of multiple 2-dimensional layers 5.

A problem with the prior art is the difficulty of providing a layer ofmetal powder with equal thickness over the full build envelope. Avariation of the powder layer thickness may be revealed by dimensionalinaccuracy of the final product.

There is a demand for additive manufacturing techniques with highermachine yield, higher final quality of manufactured part and a lesssensitive powder dispatching system.

BRIEF SUMMARY

An object of the present invention is to provide an additivemanufacturing apparatus and method suitable for additive manufacturingof three-dimensional parts which is capable of efficiently buildinghigher quality parts than prior art machines without sacrificingmaterial properties of the final product.

In a first aspect according to various embodiments of the invention itis provided a method for forming at least one three-dimensional articlethrough successive fusion of parts of a powder bed on a supportstructure, which parts correspond to successive portions of thethree-dimensional article, the method comprising the steps of: providingat least one model of the three-dimensional article, lowering thesupport structure a predetermined distance and rotating the supportstructure a predetermined angle in a first direction before applying afirst powder layer covering the lowered and rotated support structure,rotating the support structure the predetermined angle in a seconddirection opposite to the first direction before directing the at leastone first energy beam from the at least one first energy beam source atselected locations for fusing the first powder layer, directing the atleast one first energy beam from the at least one first energy beamsource at selected locations according to the model for fusing the firstpowder layer on the support structure, which is stationary, for formingfirst portions of the three-dimensional article, repeating the steps oflowering and rotating until the three-dimensional article is finished.

An exemplary advantage of at least these embodiments is that additivemanufacturing may be performed with higher yield. This is due to thefact that the angle of the manufactured part(s) relative to the powderdistributor is not constant but changed from one layer to another. Thiswill help removing repetitive errors that may arise when using a staticangle between the parts that is to be manufactured and the powderdistributor. By changing the angle of the powder distribution mechanismand the support structure onto which the three-dimensional article ismanufactured may also remove errors in the powder distribution processindependently of what is manufactured, i.e., powder distribution errorsare distributed more evenly over the manufacturing area compared to whenusing a fixed angle of the powder distribution process and supportstructure. In the latter case, errors may be stacked onto each otherfrom one layer to another, which in the end may cause not only dimensionerrors but also reduced mechanical properties of the final article.

In various example embodiments according to the present invention thepredetermined angle which the support structure is rotated is equal orunequal from one layer to another.

An exemplary advantage of using unequal rotational angle from one layerto another is that errors emanating from the powder distribution processis spread out at a larger area where they have no impact on the finalarticle or eliminated due to the fact that the angle between the powderdistributor and the previously built three-dimensional layer will notcause any powder layer inhomogeneities. An exemplary advantage of usingan equal rotational angle for a predetermined number of layers is thatthe angle is known beforehand not to cause any powder layerinhomogeneities for the-three dimensional cross sections which is to bebuilt. Another fixed rotational angle may be used for a predeterminednumber of layers if the other rotational angle gives a better powderlayer homogeneity than the previously used rotational angle. A morefavourable rotational angle may arise if the cross sections which hasbeen built is altered.

In various example embodiments according to the present invention thesupport structure is rotated by rotating the support structure aloneand/or a build tank in which the support structure is arranged.

An exemplary advantage of rotating the support structure alone andkeeping the position of the build tank fixed is that it reduces themechanical complexity of the machine. An exemplary advantage of rotatingthe build tank is that it may reduce the leakage of powder between thesupport structure and the build tank.

An advantage of various example embodiments of the present invention isthat any type of powder distribution process may be used. The rotationof the support structure a predetermined angle before powder applicationand then reposition to the original position before fusion takes placemay reduce powder distribution related errors irrespective of how thepowder distribution is made.

In a second aspect according to various embodiments of the invention itis provided an apparatus for forming a three-dimensional article throughsuccessive fusion of parts of a powder bed, which parts corresponds tosuccessive cross sections of the three-dimensional article, theapparatus comprising: a. a control unit having stored thereon a computermodel of the three-dimensional article, b. a control unit configured formoving a support structure a predetermined distance in z-direction androtating the support structure a predetermined angle in a firstdirection before applying a first powder layer covering the lowered androtated support structure, c. a control unit configured for rotating thesupport structure the predetermined angle in a second direction oppositeto the first direction before directing the at least one first energybeam from the at least one first energy beam source at selectedlocations for fusing the first powder layer, d. a control unitconfigured for directing the at least one first energy beam from the atleast one first energy beam source at selected locations according tothe model for fusing the first powder layer on the support structure,which is stationary, for forming first portions of the three-dimensionalarticle, and e. a control unit configured for repeating step b-d untilthe three-dimensional article is finished.

An exemplary advantage of at least these embodiments is that it providesfor an additive manufacturing apparatus with higher yield. This is dueto the fact that the angle of the manufactured part(s) relative to thepowder distributor is not constant but changed from one layer toanother. This will help removing repetitive errors that may arise whenusing a static angle between the parts that is to be manufactured andthe powder distributor. By changing the angle of the powder distributionmechanism and the support structure onto which the three-dimensionalarticle is manufactured may also remove errors in the powderdistribution process independently of what is manufactured, i.e., powderdistribution errors are distributed more evenly over the manufacturingarea compared to when using a fixed angle of the powder distributionprocess and support structure. In the latter case, errors may be stackedonto each other from one layer to another, which in the end may causenot only dimension errors but also reduced mechanical properties of thefinal article.

Another exemplary advantage of these embodiments is that it is equallyapplicable for any powder distribution mechanism and they are alsoindependent of the energy beam source used for fusing the powdermaterial.

In yet another aspect according to various embodiments of the inventionit is provided a method for forming at least one three-dimensionalarticle through successive fusion of parts of a powder bed on a supportstructure, which parts correspond to successive portions of thethree-dimensional article. The method comprises the steps of: providingat least one model of the three-dimensional article, lowering thesupport structure a predetermined distance and rotating the supportstructure a predetermined angle in a first direction before applying afirst powder layer covering the lowered and rotated support structure,rotating the at least one model by the predetermined angle in the firstdirection before directing the at least one first energy beam from theat least one first energy beam source at selected locations for fusingthe first powder layer, directing the at least one first energy beamfrom the at least one first energy beam source at selected locationsaccording to the model for fusing the first powder layer on the supportstructure, which is stationary, for forming first portions of thethree-dimensional article, and repeating at least the lowering and therotating steps until the three-dimensional article is finished.Exemplary advantages of this method mirror those previously detailedherein, although the same are achievable with a single mechanicalrotation versus two.

In yet another aspect according to various embodiments of the inventionit is provided a computer program product comprising at least onenon-transitory computer-readable storage medium having computer-readableprogram code portions embodied therein, the computer-readable programcode portions comprising one or more executable portions configured for:upon receipt of at least one model of a three-dimensional article,lowering a support structure a predetermined distance and rotating thesupport structure a predetermined angle in a first direction beforeapplying a first powder layer covering the lowered and rotated supportstructure, rotating the at least one model by the predetermined angle inthe first direction before directing the at least one first energy beamfrom the at least one first energy beam source at selected locations forfusing the first powder layer, directing the at least one first energybeam from the at least one first energy beam source at selectedlocations according to the model for fusing the first powder layer onthe support structure, which is stationary, for forming first portionsof the three-dimensional article, and repeating the lowering, rotating,and directing steps until the three-dimensional article is finished.Exemplary advantages of this computer program product mirror those ofthe method summarized immediately above.

In yet another aspect according to various embodiments of the inventionit is provided an apparatus for forming a three-dimensional articlethrough successive fusion of parts of a powder bed, which partscorresponds to successive cross sections of the three-dimensionalarticle, the apparatus comprising: a selectively rotatable supportstructure; at least one first energy beam; at least one control unitwith a computer model of the three-dimensional article stored thereon,the control unit being configured for: moving the support structure apredetermined distance in z-direction and rotating the support structurea predetermined angle in a first direction before applying a firstpowder layer covering the lowered and rotated support structure,rotating the computer model by the predetermined angle in the firstdirection before directing the at least one first energy beam from theat least one first energy beam source at selected locations for fusingthe first powder layer, directing the at least one first energy beamfrom the at least one first energy beam source at selected locationsaccording to the model for fusing the first powder layer on the supportstructure, which is stationary, for forming first portions of thethree-dimensional article, and repeating the moving, rotating, anddirecting steps until the three-dimensional article is finished.Exemplary advantages of this apparatus mirror those of the methodsummarized immediately above.

Herein and throughout, where an exemplary embodiment is described or anadvantage thereof is identified, such are considered and intended asexemplary and non-limiting in nature, so as to not otherwise limit orconstrain the scope and nature of the inventive concepts disclosed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be further described in the following, in anon-limiting way with reference to the accompanying drawings. Samecharacters of reference are employed to indicate corresponding similarparts throughout the several figures of the drawings:

FIG. 1 presents a first schematic side view of an additive manufacturingapparatus according to prior art;

FIG. 2 presents a second schematic side view of an additivemanufacturing apparatus according to prior art;

FIGS. 3A-3D show respective side views of an additive manufacturingmachine in different manufacturing stages according to certainembodiments of the present invention;

FIGS. 3E-G show respective side views of an additive manufacturingmachine in different manufacturing stages according to certainadditional embodiments of the present invention;

FIGS. 4A-B show exemplary schematic flow charts according to variousembodiments of the present invention;

FIG. 5 is a block diagram of an exemplary system 1020 according tovarious embodiments;

FIG. 6A is a schematic block diagram of a server 1200 according tovarious embodiments; and

FIG. 6B is a schematic block diagram of an exemplary mobile device 1300according to various embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various example embodiments of the present invention will now bedescribed more fully hereinafter with reference to the accompanyingdrawings, in which some, but not all embodiments of the invention areshown. Indeed, embodiments of the invention may be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will satisfy applicable legal requirements. Unlessotherwise defined, all technical and scientific terms used herein havethe same meaning as commonly known and understood by one of ordinaryskill in the art to which the invention relates. The term “or” is usedherein in both the alternative and conjunctive sense, unless otherwiseindicated. Like numbers refer to like elements throughout.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

The term “three-dimensional structures” and the like as used hereinrefer generally to intended or actually fabricated three-dimensionalconfigurations (e.g. of structural material or materials) that areintended to be used for a particular purpose. Such structures, etc. may,for example, be designed with the aid of a three-dimensional CAD system.

The term “two-dimensional structures” and the like as used herein refergenerally to substantially planar structures that may be considered asrespective “layers” that when taken as a whole define or otherwise formthe “three-dimensional structures” defined above. While referred to as“two-dimensional structures” it should be understood that each includesan accompanying thickness in a third dimension, albeit such that thestructures remain substantially two-dimensional in nature. As anon-limiting example, a plurality of two-dimensional structures wouldhave to be stacked atop one another so as to achieve a thicknesscomparable to that of the “three-dimensional structures” defined aboveand described elsewhere herein.

The term “electron beam” as used herein in various embodiments refers toany charged particle beam. The sources of a charged particle beam caninclude an electron gun, a linear accelerator and so on.

Various embodiments of the invention relate to a method for producingthree-dimensional objects by powder additive manufacturing, for instanceElectron Beam Melting (EBM) and/or selective laser sintering SLS orselective laser melting SLM. In various example embodiments the objectmay be wider than the sum of the beam scanning area from the energy beamsources.

FIG. 2 depicts an embodiment of a freeform fabrication or additivemanufacturing apparatus 21 according to prior art.

The apparatus 21 comprises an electron beam gun 6; deflection coils 7;two powder hoppers 4, 14; a build platform 2; a build chamber 10; apowder distributor 28; a powder bed 5; a vacuum chamber 20 and a controlunit 8.

The vacuum chamber 20 is capable of maintaining a vacuum environment bymeans of a vacuum system, which system may comprise a turbomolecularpump, a scroll pump, an ion pump and one or more valves which are wellknown to a skilled person in the art and therefore need no furtherexplanation in this context. The vacuum system is controlled by thecontrol unit 8.

The electron beam gun 6 is generating an electron beam which is used formelting or fusing together powder material provided on the buildplatform 2. The control unit 8 may be used for controlling and managingthe electron beam emitted from the electron beam gun 6. At least onefocusing coil (not shown), at least one deflection coil 7, an optionalcoil for astigmatic correction (not shown) and an electron beam powersupply (not shown) may be electrically connected to the control unit 8.In an example embodiment of the invention the electron beam gun 6generates a focusable electron beam with an accelerating voltage ofabout 15-120 kV and with a beam power in the range of 3-10 Kw. Thepressure in the vacuum chamber may be 1×10′ mbar or lower when buildingthe three-dimensional article 3 by fusing the powder layer by layer withthe energy beam.

In another embodiment a laser beam may be used for melting or fusing thepowder material. In such case tiltable mirrors may be used in the beampath in order to deflect the laser beam to a predetermined position.

The powder hoppers 4, 14 comprise the powder material to be provided onthe build platform 2 in the build chamber 10. The powder material mayfor instance be pure metals or metal alloys such as titanium, titaniumalloys, aluminum, aluminum alloys, stainless steel, Co—Cr alloys, nickelbased superalloys, etc., and the like.

The powder distributor 28 is arranged to lay down a thin layer of thepowder material on the build platform 2. During a work cycle the buildplatform 2 will be lowered successively in relation to a fixed point inthe vacuum chamber. In order to make this movement possible, the buildplatform 2 is in one embodiment of the invention arranged movably invertical direction, i.e., in the direction indicated by arrow P. Thismeans that the build platform 2 starts in an initial position, in whicha first powder material layer of necessary thickness has been laid down.Means for lowering the build platform 2 may for instance be through aservo engine equipped with a gear, adjusting screws, etc., and the like

An electron beam may be directed over the build platform 2 causing thefirst powder layer to fuse in selected locations to form a first crosssection of the three-dimensional article 3. The beam is directed overthe build platform 2 from instructions given by the control unit 8. Inthe control unit 8 instructions for how to control the electron beam foreach layer of the three-dimensional article is stored.

After a first layer is finished, i.e., the fusion of powder material formaking a first layer of the three-dimensional article 3, a second powderlayer is provided on the build platform 2. The second powder layer ispreferably distributed according to the same manner as the previouslayer. However, there might be other methods in the same additivemanufacturing machine for distributing powder onto the build platform 2.

After having distributed the second powder layer on the build platform,the energy beam is directed over the build platform 2 causing the secondpowder layer to fuse in selected locations to form a second crosssection of the three-dimensional article. Fused portions in the secondlayer may be bonded to fused portions of the first layer. The fusedportions in the first and second layer may be melted together by meltingnot only the powder in the uppermost layer but also remelting at least afraction of a thickness of a layer directly below the uppermost layer.

An optional preheating of the powder layer to a temperature below themelting point of the powders may be performed before the actual fusingof the powder takes place at selected areas.

Performing the melting by scanning with a focused beam in the areacorresponding to a predetermined cross section of the model stored inthe control unit 8.

In another embodiment the build platform 2 may be provided in anenclosable chamber provided with ambient air and atmosphere pressure. Instill another example embodiment the work plate may be provided in openair. In those two cases the high energy beam fusing the powder materialmay be one or a plurality of laser beams.

FIGS. 3A-3D show respective side views of an additive manufacturingmachine in different manufacturing stages according to the presentinvention.

FIG. 3A comprises a first powder hopper 4 with powder 67, a secondpowder hopper 14 with powder 167, a powder distributor 28, a powdertable 40, a build chamber 10, a build platform 2. The energy beam(s) andits energy beam source(s) and beam deflection mechanism for fusing thepowder layers have been left out for clarity reasons only.

A predetermined amount of powder 68 from the first powder hopper 4 maybe provided on the powder table 40 between the powder distributor 28 andthe build chamber 10. This predetermined amount of powder 68 may beprovided on the powder table 40 by raising a floor 65 in the powderhopper 4 a predetermined distance. In FIG. 3A the predetermined amountof powder is created by raising the floor 65 from a position C to aposition D. The predetermined amount of powder 68 then provided abovethe top surface A of the powder table 40 in the powder hopper 4, may beraked off by the powder distributor 28 from the powder hopper 4 to thepowder table 40. The predetermined amount of powder 68 may be raked offfrom the first powder hopper 4 to an area between the powder hopper 4and the build chamber 10, i,e, onto the powder table 40, or directly tothe build chamber 10 if there is no space between the build chamber 10and the first powder hopper 4.

The build platform 2 is arranged at a position denoted by B, which islower than a position of the powder table 40 which is denoted by A. Thedifference in height between the powder table 40 and the top surface ofthe build platform 2 or a previous partly fused powder layer willrepresent the thickness of the powder layer which is to be fused inselected location according to the model stored in the control unit.

Before a new layer of powder material is applied on top of the buildplatform 2, the build platform 2 is not only lowered in order to createthe space for a new powder layer but also rotated a predetermined angledenoted by arrow 80 in FIG. 3A. The angle of rotation may be between0°-90° from its original position in a clockwise direction or 0°-90° ina counter clockwise direction. In an example embodiment the angle is 72degrees either clockwise or counter clockwise. In another exampleembodiment the angle is 40 degrees either clockwise or counterclockwise. By rotating the build platform 2 a predetermined angle beforeapplying the powder layer instead of always keeping the build platform 2at a fixed angular position will decrease the likelihood of dimensionalinstability due to the fact that possible powder distribution errorsfrom one layer may not add up with powder distribution errors in anotherlayer. The powder distribution errors may arise from previously fusedareas having a different height compared to the non-fused areas. Bychanging the angle of the previously built areas with respect to apowder distributor 28 from one layer to another, the likelihood ofbuilding up large dimensional errors may be reduced. The build platformis rotated the predetermined angle with respect to the powderdistribution mechanism in a clockwise or counter clockwise directionfrom its original position before the powder application is started. Inan example embodiment the rotation of the build platform 2 may be with afirst predetermined angle before a first layer is to be applied and asecond predetermined angle before a second layer is to be applied. Thefirst and second angles may be different. The first predetermined angleof rotation may be in a clockwise direction and the second predeterminedangle of rotation may be in a counter clockwise direction.

In another example embodiment the predetermined angle is randomlyselected to be any angle between 0-90 degrees for a predetermined numberof layers in either clockwise direction or counter clockwise direction.

The build platform 2 may be rotated by rotating the axis 90 supportingthe build platform 2. In another example embodiment the build platform 2may be rotated by rotating the build tank 10 together with the buildplatform 2.

FIG. 3B illustrates the process step in which the powder taken from thepowder hopper 4 is distributed over the build platform 2. Whiledistributing the powder material over the build platform 2, the buildplatform 2 is in a stationary condition, i.e., neither moving downwardsnor rotating.

FIG. 3C illustrates a step made after the powder layer has been appliedbut before the powder layer is irradiated with a high energy beam forfusing the powder in selected locations. In FIG. 3C the build platform 2is rotated back to its original position by rotating the build platform2 the predetermined angle in an opposite direction compared to thedirection the build platform 2 was rotated prior to applying the powderlayer. By the rotation one makes sure that the coordinate system of thehigh energy beam and the coordinate system of the build platform 2 arealigned to each other. In an example embodiment one or a plurality ofalignment marks may be used for returning the build platform 2 to itsoriginal position. The alignment marks may be detected by a camerasystem. The detected alignment marks may either be compared with areference position or alternatively a first alignment mark may beprovided on the build platform 2 and a second alignment mark may bearranged in a fixed position. The fixed alignment mark and the alignmentmark on the build platform 2 should be arranged in a predetermined waywhen the build platform 2 is in its original position. Other means formaking sure the build platform 2 is returning to the same position isalso possible, such as alignment marks detected by camera or illuminatedby laser light are also possible. The alignment marks may be arranged onthe backside of the build platform 2. In an alternative embodiment theoriginal position may be validated by detecting an electrical devicerotating the build platform 2 or build platform 2 together with thebuild tank. The electrical device making the rotation may for instancebe a step motor having a gear adapted to and engaging with a gear on thebuild platform 2 or the build tank 10.

In FIG. 3D the powder layer is radiated in selected locations by thehigh energy beam 75 for heating and/or melting the powder layer 33. Thebuild platform 2 is stationary in its original position while meltingthe powder layer at the selected locations. In FIG. 3D only one beam isillustrated, but two or more high energy beams may also be used in theheating and/or melting process. The one or plurality of beams may be ofthe same type or of different type. Laser beams and/or electron beamsmay be used for melting and/or heating the powder layer 33.

FIGS. 3E-G show respective side views of an additive manufacturingmachine in different manufacturing stages according to anotherembodiment of the present invention.

FIG. 3E comprises a first powder hopper 4 with powder 67, a secondpowder hopper 14 with powder 167, a powder distributor 28, a powdertable 40, a build chamber 10, a build platform 2. The energy beam(s) andits energy beam source(s) and beam deflection mechanism for fusing thepowder layers have been left out for clarity reasons only.

A predetermined amount of powder 68 from the first powder hopper 4 maybe provided on the powder table 40 between the powder distributor 28 andthe build chamber 10. This predetermined amount of powder 68 may beprovided on the powder table 40 by raising a floor 65 in the powderhopper 4 a predetermined distance. In FIG. 3E the predetermined amountof powder is created by raising the floor 65 from a position C to aposition D. The predetermined amount of powder 68 then provided abovethe top surface A of the powder table 40 in the powder hopper 4, may beraked off by the powder distributor 28 from the powder hopper 4 to thepowder table 40. The predetermined amount of powder 68 may be raked offfrom the first powder hopper 4 to an area between the powder hopper 4and the build chamber 10, i,e, onto the powder table 40, or directly tothe build chamber 10 if there is no space between the build chamber 10and the first powder hopper 4.

The build platform 2 is arranged at a position denoted by B, which islower than a position of the powder table 40 which is denoted by A. Thedifference in height between the powder table 40 and the top surface ofthe build platform 2 or a previous partly fused powder layer willrepresent the thickness of the powder layer which is to be fused inselected location according to the model stored in the control unit.

Before a new layer of powder material is applied on top of the buildplatform 2, the build platform 2 is not only lowered in order to createthe space for a new powder layer but also rotated a predetermined angledenoted by arrow 80 in FIG. 3E. The angle of rotation may be between0°-90° from its original position in a clockwise direction or 0°-90° ina counter clockwise direction. In an example embodiment the angle is 72degrees either clockwise or counter clockwise. In another exampleembodiment the angle is 20 degrees either clockwise or counterclockwise. By rotating the build platform 2 a predetermined angle beforeapplying the powder layer instead of always keeping the build platform 2at a fixed angular position the likelihood of dimensional instability isdecreased due to the fact that possible powder distribution errors fromone layer may not add up with powder distribution errors in anotherlayer. The powder distribution errors may arise from previously fusedareas having a different height compared to the non-fused areas. Bychanging the angle of the previously built areas with respect to apowder distributor 28 from one layer to another, the likelihood ofbuilding up large dimensional errors may be reduced. The build platformis rotated the predetermined angle with respect to the powderdistribution mechanism in a clockwise or counter clockwise directionfrom its original position before the powder application is started. Inan example embodiment the rotation of the build platform 2 may be with afirst predetermined angle before a first layer is to be applied and asecond predetermined angle before a second layer is to be applied. Thefirst and second angles may be different. The first predetermined angleof rotation may be in a clockwise direction and the second predeterminedangle of rotation may be in a counter clockwise direction.

In another example embodiment the predetermined angle is randomlyselected to be any angle between 0-90 degrees for a predetermined numberof layers in either clockwise direction or counter clockwise direction.The build platform 2 may be rotated by rotating the axis 90 supportingthe build platform 2. In another example embodiment the build platform 2may be rotated by rotating the build tank 10 together with the buildplatform 2.

FIG. 3F illustrates the process step in which the powder taken from thepowder hopper 4 is distributed over the build platform 2. Whiledistributing the powder material over the build platform 2, the buildplatform 2 is in a stationary condition, i.e., neither moving downwardsnor rotating.

In FIG. 3G the powder layer is next radiated in selected locations bythe high energy beam 75 for heating and/or melting the powder layer 33.The build platform 2 remains stationary in the same position as in FIG.3F while melting the powder layer at the selected locations. In FIG. 3Gonly one beam is illustrated, but two or more high energy beams may alsobe used in the heating and/or melting process. The one or plurality ofbeams may be of the same type or of different type. Laser beams and/orelectron beams may be used for melting and/or heating the powder layer33.

Notably, in FIG. 3G, as compared to FIG. 3D, the build platform 2 is notprior (as in FIG. 3C) rotated back to its original position. Instead, inFIG. 3G, the build platform remains in the rotated position achieved inFIG. 3F. Before fusing or radiation that occurs in FIG. 3G, though, theat least one model of the three-dimensional article that is provided(e.g., via a CAD (Computer Aided Design) tool, as described elsewhereherein) may be rotated an angle that corresponds to the predeterminedangle by which the build platform 2 (and/or build tank 10) is rotated inFIG. 3F. As a result, only one mechanical rotation of the build platform2 is needed per layer, with the second mechanical rotation provided inother embodiments described herein being replaced with acomputer-generated rotation of the CAD file or model, thus providing arotation of the coordinate system utilized by the high energy beamduring heating and/or melting of the powder layer 33. In other words, bythe rotation of the model (without a second rotation of the supportsurface or build platform 2, one can nevertheless ensure that thecoordinate system of the high energy beam and the coordinate system ofthe build platform 2 are aligned to each other.

Rotation of the CAD file or model may be clockwise or counter-clockwise.The rotation of the CAD file may also be different for different layers,much like the rotation of the build platform 2. It is also possible torotate the CAD and/or the build platform 2 in clockwise andcounter-clockwise directions in the same build of a three-dimensionalmulti-layer object, provided that the CAD file is always rotated in thesame direction as the build platform 2 for any particular layer.

Various embodiments of this invention concern the provision of arotation of the build platform 2 from its original position prior toapplying a new powder layer and then rotating an associated CAD file(i.e., model) in a corresponding manner when the powder layer has beenapplied but before the powder layer is radiated by the high energy beamfor fusing and/or heating at selected locations. In an exampleembodiment of the present invention the axis of rotation may be verticaland the build platform 2 may be annular.

The build platform 2 may either be rotated by rotating the axis 90supporting the build platform 2 or rotating the build tank 10 togetherwith the build platform 2 with respect to a powder distributionmechanism. A rotation of the build tank 10 may be applied from itsoutside.

A position of the build tank 10 and work plate 2 may be measured andfeedback to the control unit 8.

It must be understood that the present invention is potentiallyapplicable to any type of layer wise rapid prototyping and additivemanufacturing machines, and to other machines using the layer-on-layerfabrication technique, including non-metallic material.

The electron beam source generating an electron beam may be used formelting or fusing together powder material 33 provided on the work plate2. The control unit 8 may be used for controlling and managing theelectron and/or laser beams emitted from at least one electron beamsource and/or at least one laser beam source. The electron beams and/orlaser beams may be deflected between its first extreme position and itssecond extreme position.

The powder storage 4, 14 may comprise the metal powder material 67, 167to be provided on the work plate 2. The metal powder material may forinstance be pure metals or metal alloys such as titanium, titaniumalloys, aluminum, aluminum alloys, stainless steel, Co—Cr—W alloy,Ni-based alloys, Titanium aluminides, Niobium, silicon nitride,molybdenum disilicide and the like.

In FIG. 4A it is depicted a flow chart of an example embodiment of amethod for forming at least one three-dimensional article throughsuccessive fusion of parts of a powder bed on a support structure, whichparts correspond to successive portions of the three-dimensionalarticle.

In a first step denoted 410 at least one model of the three-dimensionalarticle is provided. The model may be generated by a CAD (Computer AidedDesign) tool. The model may be sliced into a number of slicesrepresenting the fused powder layers which is going to form the physicalthree-dimensional article.

In a second step denoted 420 the support structure is lowered apredetermined distance and rotated a predetermined angle in a firstdirection before applying a first powder layer covering the lowered androtated support structure. The rotation may be performed with respect toa powder distribution mechanism. The predetermined angle may be between0°-90° in a clockwise direction or 0°-90° in a counter clockwisedirection. Alternatively the predetermined angle is 0-180 degrees fromthe original position. When using 0-180 degrees it will take longer timeto go to the extreme position 180 and back from the extreme position tothe original position compared to if using 0-90 in clockwise directionand 0-90 in counter clockwise direction. Given that the speed ofrotation is the same in both case it will be a reduction by a factor 2in the latter case with clockwise and counter clockwise rotation. Therotation and lowering may be performed simultaneously or as separatesteps. In the latter case the rotation of the support structure or thebuild tank together with the support structure may be performed beforelowering or vice versa.

In a third step denoted by 430 the support structure is rotated thepredetermined angle in a second direction opposite to the firstdirection before directing the at least one first energy beam from theat least one first energy beam source at selected locations for fusingthe first powder layer. Here the support structure 2 is rotated back tothe original position, which position is aligned with the high energybeam coordinate system. By returning back to the original position whenfusing the powder material there is no need for coordinatetransformation as would be necessary if the fusing position is alteredfrom one layer to another.

In a fourth step denoted by 440 the at least one first energy beam isdirected from the at least one first energy beam source at selectedlocations according to the model for fusing the first powder layer onthe support structure, which is stationary, for forming first portionsof the three-dimensional article. The at least one first energy beam maybe at least one laser beam and/or at least one electron beam.

In a fifth step denoted by 450 step 420 to 440 is repeated until thethree-dimensional article is finished.

In FIG. 4B it is depicted a flow chart of another example embodiment ofa method for forming at least one three-dimensional article throughsuccessive fusion of parts of a powder bed on a support structure, whichparts correspond to successive portions of the three-dimensionalarticle.

In a first step denoted 510 at least one model of the three-dimensionalarticle is provided. The model may be generated by a CAD (Computer AidedDesign) tool. The model may be sliced into a number of slicesrepresenting the fused powder layers which is going to form the physicalthree-dimensional article.

In a second step denoted 520 the support structure is lowered apredetermined distance and rotated a predetermined angle in a firstdirection before applying a first powder layer covering the lowered androtated support structure. The rotation may be performed with respect toa powder distribution mechanism. The predetermined angle may be between0°-90° in a clockwise direction or 0°-90° in a counter clockwisedirection. Alternatively the predetermined angle is 0-180 degrees fromthe original position. When using 0-180 degrees it will take longer timeto go to the extreme position 180 and back from the extreme position tothe original position compared to if using 0-90 in clockwise directionand 0-90 in counter clockwise direction. Given that the speed ofrotation is the same in both case it will be a reduction by a factor 2in the latter case with clockwise and counter clockwise rotation. Therotation and lowering may be performed simultaneously or as separatesteps. In the latter case the rotation of the support structure or thebuild tank together with the support structure may be performed beforelowering or vice versa.

In a third step denoted by 530 the support structure remains in theposition obtained during step 520 (i.e., it is not further rotated).Instead, as compared to step 430, during step 530 the at least one modelof the three-dimensional article provided in step 510 is electronicallyrotated. Rotation of the model, as generated by a CAD (Computer AidedDesign) tool, is done by an angle corresponding in value and directionto the rotation of the support structure in step 520. In other words, itis also possible to rotate the CAD file (and thus the coordinate systemreferenced therein) in clockwise and counter-clockwise directions in thesame build of a three-dimensional multi-layer object, provided that theCAD file is always rotated in the same direction as the build platform 2for any particular layer. In at least this embodiment, only onemechanical rotation of the build platform 2 is needed per layer, withthe second mechanical rotation provided in other embodiments describedherein being replaced with a computer-generated rotation of the CAD fileor model, thus providing a rotation of the coordinate system utilized bythe high energy beam during heating and/or melting of the powder layer33 (see step 540).

In a fourth step denoted by 540 the at least one first energy beam isdirected from the at least one first energy beam source at selectedlocations according to the model for fusing the first powder layer onthe support structure, which is stationary, for forming first portionsof the three-dimensional article. The at least one first energy beam maybe at least one laser beam and/or at least one electron beam.

In a fifth step denoted by 550, step 520 to 540 is repeated until thethree-dimensional article is finished.

Preheating of the powder with the purpose of heating the powderparticles to a predetermined temperature below its melting temperaturemay be performed at any stage, i.e., during powder application, duringrotation and/or lowering of the support structure and/or during fusionof the powder particles but at other regions where fusion is not takingplace.

In another aspect of the invention it is provided a program elementconfigured and arranged when executed on a computer to implement amethod for forming at least one three-dimensional article throughsuccessive fusion of parts of a powder bed, which parts correspond tosuccessive portions of the three-dimensional article. The programelement may be installed in a computer readable storage medium. Thecomputer readable storage medium may be the control unit 10 or anotherand separate control unit, as may be desirable. The computer readablestorage medium and the program element, which may comprisecomputer-readable program code portions embodied therein, may further becontained within a non-transitory computer program product. Furtherdetails regarding these features and configurations are provided, inturn, below.

As mentioned, various embodiments of the present invention may beimplemented in various ways, including as non-transitory computerprogram products. A computer program product may include anon-transitory computer-readable storage medium storing applications,programs, program modules, scripts, source code, program code, objectcode, byte code, compiled code, interpreted code, machine code,executable instructions, and/or the like (also referred to herein asexecutable instructions, instructions for execution, program code,and/or similar terms used herein interchangeably). Such non-transitorycomputer-readable storage media include all computer-readable media(including volatile and non-volatile media).

In one embodiment, a non-volatile computer-readable storage medium mayinclude a floppy disk, flexible disk, hard disk, solid-state storage(SSS) (e.g., a solid state drive (SSD), solid state card (SSC), solidstate module (SSM)), enterprise flash drive, magnetic tape, or any othernon-transitory magnetic medium, and/or the like. A non-volatilecomputer-readable storage medium may also include a punch card, papertape, optical mark sheet (or any other physical medium with patterns ofholes or other optically recognizable indicia), compact disc read onlymemory (CD-ROM), compact disc compact disc-rewritable (CD-RW), digitalversatile disc (DVD), Blu-ray disc (BD), any other non-transitoryoptical medium, and/or the like. Such a non-volatile computer-readablestorage medium may also include read-only memory (ROM), programmableread-only memory (PROM), erasable programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), flashmemory (e.g., Serial, NAND, NOR, and/or the like), multimedia memorycards (MMC), secure digital (SD) memory cards, SmartMedia cards,CompactFlash (CF) cards, Memory Sticks, and/or the like. Further, anon-volatile computer-readable storage medium may also includeconductive-bridging random access memory (CBRAM), phase-change randomaccess memory (PRAM), ferroelectric random-access memory (FeRAM),non-volatile random-access memory (NVRAM), magnetoresistiverandom-access memory (MRAM), resistive random-access memory (RRAM),Silicon-Oxide-Nitride-Oxide-Silicon memory (SONOS), floating junctiongate random access memory (FJG RAM), Millipede memory, racetrack memory,and/or the like.

In one embodiment, a volatile computer-readable storage medium mayinclude random access memory (RAM), dynamic random access memory (DRAM),static random access memory (SRAM), fast page mode dynamic random accessmemory (FPM DRAM), extended data-out dynamic random access memory (EDODRAM), synchronous dynamic random access memory (SDRAM), double datarate synchronous dynamic random access memory (DDR SDRAM), double datarate type two synchronous dynamic random access memory (DDR2 SDRAM),double data rate type three synchronous dynamic random access memory(DDR3 SDRAM), Rambus dynamic random access memory (RDRAM), TwinTransistor RAM (TTRAM), Thyristor RAM (T-RAM), Zero-capacitor (Z-RAM),Rambus in-line memory module (RIMM), dual in-line memory module (DIMM),single in-line memory module (SIMM), video random access memory VRAM,cache memory (including various levels), flash memory, register memory,and/or the like. It will be appreciated that where embodiments aredescribed to use a computer-readable storage medium, other types ofcomputer-readable storage media may be substituted for or used inaddition to the computer-readable storage media described above.

As should be appreciated, various embodiments of the present inventionmay also be implemented as methods, apparatus, systems, computingdevices, computing entities, and/or the like, as have been describedelsewhere herein. As such, embodiments of the present invention may takethe form of an apparatus, system, computing device, computing entity,and/or the like executing instructions stored on a computer-readablestorage medium to perform certain steps or operations. However,embodiments of the present invention may also take the form of anentirely hardware embodiment performing certain steps or operations.

Various embodiments are described below with reference to block diagramsand flowchart illustrations of apparatuses, methods, systems, andcomputer program products. It should be understood that each block ofany of the block diagrams and flowchart illustrations, respectively, maybe implemented in part by computer program instructions, e.g., aslogical steps or operations executing on a processor in a computingsystem. These computer program instructions may be loaded onto acomputer, such as a special purpose computer or other programmable dataprocessing apparatus to produce a specifically-configured machine, suchthat the instructions which execute on the computer or otherprogrammable data processing apparatus implement the functions specifiedin the flowchart block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including computer-readableinstructions for implementing the functionality specified in theflowchart block or blocks. The computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operational steps to be performed on the computeror other programmable apparatus to produce a computer-implementedprocess such that the instructions that execute on the computer or otherprogrammable apparatus provide operations for implementing the functionsspecified in the flowchart block or blocks.

Accordingly, blocks of the block diagrams and flowchart illustrationssupport various combinations for performing the specified functions,combinations of operations for performing the specified functions andprogram instructions for performing the specified functions. It shouldalso be understood that each block of the block diagrams and flowchartillustrations, and combinations of blocks in the block diagrams andflowchart illustrations, could be implemented by special purposehardware-based computer systems that perform the specified functions oroperations, or combinations of special purpose hardware and computerinstructions.

FIG. 5 is a block diagram of an exemplary system 1020 that can be usedin conjunction with various embodiments of the present invention. In atleast the illustrated embodiment, the system 1020 may include one ormore central computing devices 1110, one or more distributed computingdevices 1120, and one or more distributed handheld or mobile devices1300, all configured in communication with a central server 1200 (orcontrol unit) via one or more networks 1130. While FIG. 5 illustratesthe various system entities as separate, standalone entities, thevarious embodiments are not limited to this particular architecture.

According to various embodiments of the present invention, the one ormore networks 1130 may be capable of supporting communication inaccordance with any one or more of a number of second-generation (2G),2.5G, third-generation (3G), and/or fourth-generation (4G) mobilecommunication protocols, or the like. More particularly, the one or morenetworks 1130 may be capable of supporting communication in accordancewith 2G wireless communication protocols IS-136 (TDMA), GSM, and IS-95(CDMA). Also, for example, the one or more networks 1130 may be capableof supporting communication in accordance with 2.5G wirelesscommunication protocols GPRS, Enhanced Data GSM Environment (EDGE), orthe like. In addition, for example, the one or more networks 1130 may becapable of supporting communication in accordance with 3G wirelesscommunication protocols such as Universal Mobile Telephone System (UMTS)network employing Wideband Code Division Multiple Access (WCDMA) radioaccess technology. Some narrow-band AMPS (NAMPS), as well as TACS,network(s) may also benefit from embodiments of the present invention,as should dual or higher mode mobile stations (e.g., digital/analog orTDMA/CDMA/analog phones). As yet another example, each of the componentsof the system 1020 may be configured to communicate with one another inaccordance with techniques such as, for example, radio frequency (RF),Bluetooth™ infrared (IrDA), or any of a number of different wired orwireless networking techniques, including a wired or wireless PersonalArea Network (“PAN”), Local Area Network (“LAN”), Metropolitan AreaNetwork (“MAN”), Wide Area Network (“WAN”), or the like.

Although the device(s) 1110-1300 are illustrated in FIG. 5 ascommunicating with one another over the same network 1130, these devicesmay likewise communicate over multiple, separate networks.

According to one embodiment, in addition to receiving data from theserver 1200, the distributed devices 1110, 1120, and/or 1300 may befurther configured to collect and transmit data on their own. In variousembodiments, the devices 1110, 1120, and/or 1300 may be capable ofreceiving data via one or more input units or devices, such as a keypad,touchpad, barcode scanner, radio frequency identification (RFID) reader,interface card (e.g., modem, etc.) or receiver. The devices 1110, 1120,and/or 1300 may further be capable of storing data to one or morevolatile or non-volatile memory modules, and outputting the data via oneor more output units or devices, for example, by displaying data to theuser operating the device, or by transmitting data, for example over theone or more networks 1130.

In various embodiments, the server 1200 includes various systems forperforming one or more functions in accordance with various embodimentsof the present invention, including those more particularly shown anddescribed herein. It should be understood, however, that the server 1200might include a variety of alternative devices for performing one ormore like functions, without departing from the spirit and scope of thepresent invention. For example, at least a portion of the server 1200,in certain embodiments, may be located on the distributed device(s)1110, 1120, and/or the handheld or mobile device(s) 1300, as may bedesirable for particular applications. As will be described in furtherdetail below, in at least one embodiment, the handheld or mobiledevice(s) 1300 may contain one or more mobile applications 1330 whichmay be configured so as to provide a user interface for communicationwith the server 1200, all as will be likewise described in furtherdetail below.

FIG. 6A is a schematic diagram of the server 1200 according to variousembodiments. The server 1200 includes a processor 1230 that communicateswith other elements within the server via a system interface or bus1235. Also included in the server 1200 is a display/input device 1250for receiving and displaying data. This display/input device 1250 maybe, for example, a keyboard or pointing device that is used incombination with a monitor. The server 1200 further includes memory1220, which typically includes both read only memory (ROM) 1226 andrandom access memory (RAM) 1222. The server's ROM 1226 is used to storea basic input/output system 1224 (BIOS), containing the basic routinesthat help to transfer information between elements within the server1200. Various ROM and RAM configurations have been previously describedherein.

In addition, the server 1200 includes at least one storage device orprogram storage 210, such as a hard disk drive, a floppy disk drive, aCD Rom drive, or optical disk drive, for storing information on variouscomputer-readable media, such as a hard disk, a removable magnetic disk,or a CD-ROM disk. As will be appreciated by one of ordinary skill in theart, each of these storage devices 1210 are connected to the system bus1235 by an appropriate interface. The storage devices 1210 and theirassociated computer-readable media provide nonvolatile storage for apersonal computer. As will be appreciated by one of ordinary skill inthe art, the computer-readable media described above could be replacedby any other type of computer-readable media known in the art. Suchmedia include, for example, magnetic cassettes, flash memory cards,digital video disks, and Bernoulli cartridges.

Although not shown, according to an embodiment, the storage device 1210and/or memory of the server 1200 may further provide the functions of adata storage device, which may store historical and/or current deliverydata and delivery conditions that may be accessed by the server 1200. Inthis regard, the storage device 1210 may comprise one or more databases.The term “database” refers to a structured collection of records or datathat is stored in a computer system, such as via a relational database,hierarchical database, or network database and as such, should not beconstrued in a limiting fashion.

A number of program modules (e.g., exemplary modules 1400-1700)comprising, for example, one or more computer-readable program codeportions executable by the processor 1230, may be stored by the variousstorage devices 1210 and within RAM 1222. Such program modules may alsoinclude an operating system 1280. In these and other embodiments, thevarious modules 1400, 1500, 1600, 1700 control certain aspects of theoperation of the server 1200 with the assistance of the processor 1230and operating system 1280. In still other embodiments, it should beunderstood that one or more additional and/or alternative modules mayalso be provided, without departing from the scope and nature of thepresent invention.

In various embodiments, the program modules 1400, 1500, 1600, 1700 areexecuted by the server 1200 and are configured to generate one or moregraphical user interfaces, reports, instructions, and/ornotifications/alerts, all accessible and/or transmittable to varioususers of the system 1020. In certain embodiments, the user interfaces,reports, instructions, and/or notifications/alerts may be accessible viaone or more networks 1130, which may include the Internet or otherfeasible communications network, as previously discussed.

In various embodiments, it should also be understood that one or more ofthe modules 1400, 1500, 1600, 1700 may be alternatively and/oradditionally (e.g., in duplicate) stored locally on one or more of thedevices 1110, 1120, and/or 1300 and may be executed by one or moreprocessors of the same. According to various embodiments, the modules1400, 1500, 1600, 1700 may send data to, receive data from, and utilizedata contained in one or more databases, which may be comprised of oneor more separate, linked and/or networked databases.

Also located within the server 1200 is a network interface 1260 forinterfacing and communicating with other elements of the one or morenetworks 1130. It will be appreciated by one of ordinary skill in theart that one or more of the server 1200 components may be locatedgeographically remotely from other server components. Furthermore, oneor more of the server 1200 components may be combined, and/or additionalcomponents performing functions described herein may also be included inthe server.

While the foregoing describes a single processor 1230, as one ofordinary skill in the art will recognize, the server 1200 may comprisemultiple processors operating in conjunction with one another to performthe functionality described herein. In addition to the memory 1220, theprocessor 1230 can also be connected to at least one interface or othermeans for displaying, transmitting and/or receiving data, content or thelike. In this regard, the interface(s) can include at least onecommunication interface or other means for transmitting and/or receivingdata, content or the like, as well as at least one user interface thatcan include a display and/or a user input interface, as will bedescribed in further detail below. The user input interface, in turn,can comprise any of a number of devices allowing the entity to receivedata from a user, such as a keypad, a touch display, a joystick or otherinput device.

Still further, while reference is made to the “server” 1200, as one ofordinary skill in the art will recognize, embodiments of the presentinvention are not limited to traditionally defined server architectures.Still further, the system of embodiments of the present invention is notlimited to a single server, or similar network entity or mainframecomputer system. Other similar architectures including one or morenetwork entities operating in conjunction with one another to providethe functionality described herein may likewise be used withoutdeparting from the spirit and scope of embodiments of the presentinvention. For example, a mesh network of two or more personal computers(PCs), similar electronic devices, or handheld portable devices,collaborating with one another to provide the functionality describedherein in association with the server 1200 may likewise be used withoutdeparting from the spirit and scope of embodiments of the presentinvention.

According to various embodiments, many individual steps of a process mayor may not be carried out utilizing the computer systems and/or serversdescribed herein, and the degree of computer implementation may vary, asmay be desirable and/or beneficial for one or more particularapplications.

FIG. 6B provides an illustrative schematic representative of a mobiledevice 1300 that can be used in conjunction with various embodiments ofthe present invention. Mobile devices 1300 can be operated by variousparties. As shown in FIG. 6B, a mobile device 1300 may include anantenna 1312, a transmitter 1304 (e.g., radio), a receiver 1306 (e.g.,radio), and a processing element 1308 that provides signals to andreceives signals from the transmitter 1304 and receiver 1306,respectively.

The signals provided to and received from the transmitter 1304 and thereceiver 1306, respectively, may include signaling data in accordancewith an air interface standard of applicable wireless systems tocommunicate with various entities, such as the server 1200, thedistributed devices 1110, 1120, and/or the like. In this regard, themobile device 1300 may be capable of operating with one or more airinterface standards, communication protocols, modulation types, andaccess types. More particularly, the mobile device 1300 may operate inaccordance with any of a number of wireless communication standards andprotocols. In a particular embodiment, the mobile device 1300 mayoperate in accordance with multiple wireless communication standards andprotocols, such as GPRS, UMTS, CDMA2000, 1×RTT, WCDMA, TD-SCDMA, LTE,E-UTRAN, EVDO, HSPA, HSDPA, Wi-Fi, WiMAX, UWB, IR protocols, Bluetoothprotocols, USB protocols, and/or any other wireless protocol.

Via these communication standards and protocols, the mobile device 1300may according to various embodiments communicate with various otherentities using concepts such as Unstructured Supplementary Service data(USSD), Short Message Service (SMS), Multimedia Messaging Service (MMS),Dual-Tone Multi-Frequency Signaling (DTMF), and/or Subscriber IdentityModule Dialer (SIM dialer). The mobile device 1300 can also downloadchanges, add-ons, and updates, for instance, to its firmware, software(e.g., including executable instructions, applications, programmodules), and operating system.

According to one embodiment, the mobile device 1300 may include alocation determining device and/or functionality. For example, themobile device 1300 may include a GPS module adapted to acquire, forexample, latitude, longitude, altitude, geocode, course, and/or speeddata. In one embodiment, the GPS module acquires data, sometimes knownas ephemeris data, by identifying the number of satellites in view andthe relative positions of those satellites.

The mobile device 1300 may also comprise a user interface (that caninclude a display 1316 coupled to a processing element 1308) and/or auser input interface (coupled to a processing element 308). The userinput interface can comprise any of a number of devices allowing themobile device 1300 to receive data, such as a keypad 1318 (hard orsoft), a touch display, voice or motion interfaces, or other inputdevice. In embodiments including a keypad 1318, the keypad can include(or cause display of) the conventional numeric (0-9) and related keys(#, *), and other keys used for operating the mobile device 1300 and mayinclude a full set of alphabetic keys or set of keys that may beactivated to provide a full set of alphanumeric keys. In addition toproviding input, the user input interface can be used, for example, toactivate or deactivate certain functions, such as screen savers and/orsleep modes.

The mobile device 1300 can also include volatile storage or memory 1322and/or non-volatile storage or memory 1324, which can be embedded and/ormay be removable. For example, the non-volatile memory may be ROM, PROM,EPROM, EEPROM, flash memory, MMCs, SD memory cards, Memory Sticks,CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, and/or the like. Thevolatile memory may be RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDRSDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cachememory, register memory, and/or the like. The volatile and non-volatilestorage or memory can store databases, database instances, databasemapping systems, data, applications, programs, program modules, scripts,source code, object code, byte code, compiled code, interpreted code,machine code, executable instructions, and/or the like to implement thefunctions of the mobile device 1300.

The mobile device 1300 may also include one or more of a camera 1326 anda mobile application 1330. The camera 1326 may be configured accordingto various embodiments as an additional and/or alternative datacollection feature, whereby one or more items may be read, stored,and/or transmitted by the mobile device 1300 via the camera. The mobileapplication 1330 may further provide a feature via which various tasksmay be performed with the mobile device 1300. Various configurations maybe provided, as may be desirable for one or more users of the mobiledevice 1300 and the system 1020 as a whole.

It will be appreciated that many variations of the above systems andmethods are possible, and that deviation from the above embodiments arepossible, but yet within the scope of the claims. Many modifications andother embodiments of the invention set forth herein will come to mind toone skilled in the art to which these inventions pertain having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings. Such modifications may, for example, involve usinga different numbers of energy beam sources than the exemplified twoenergy beam sources. There may be a mixture between different kinds ofenergy beam sources such as laser beam sources and electron beamsources. In various example embodiments only a plurality of laser beamsources are used. Other electrically conductive materials than puremetallic powder may be used such as electrically conductive powders ofpolymers and electrically conductive powder of ceramics. Therefore, itis to be understood that the inventions are not to be limited to thespecific embodiments disclosed and that modifications and otherembodiments are intended to be included within the scope of the appendedclaims. Although specific terms are employed herein, they are used in ageneric and descriptive sense only and not for purposes of limitation.

The invention claimed is:
 1. A method for forming at least onethree-dimensional article through successive fusion of parts of a powderbed on a support structure, which parts correspond to successiveportions of the three-dimensional article, the method comprising thesteps of: providing at least one model of the three-dimensional article,lowering the support structure a predetermined distance and rotating thesupport structure a predetermined angle in a first direction beforeapplying a first powder layer covering the lowered and rotated supportstructure, rotating the support structure the predetermined angle in asecond direction opposite to the first direction before directing the atleast one first energy beam from the at least one first energy beamsource at selected locations for fusing the first powder layer,directing the at least one first energy beam from the at least one firstenergy beam source at selected locations according to the model forfusing the first powder layer on the support structure, which isstationary, for forming first portions of the three-dimensional article,repeating at least the lowering, the rotating, and the directing stepsuntil the three-dimensional article is finished.
 2. The method accordingto claim 1, wherein the predetermined angle which the support structureis rotated is equal or unequal from one layer to another.
 3. The methodaccording to claim 1, wherein the support structure is rotated by eitherrotating the support structure alone or by rotating a build tank inwhich the support structure is arranged.
 4. The method according toclaim 1, wherein the predetermined angle is less than 30°.
 5. The methodaccording to claim 1, wherein the powder layer is provided by a powderdistributor, which powder distributor is pushing a predetermined amountof powder to be applied in front of the powder distributor over andabove the support structure.
 6. The method according to claim 1, whereinthe rotational axis of the support structure is along the Z-axis and theat least one beam is fusing in an X-Y plane.
 7. The method according toclaim 1, wherein the support structure is a horizontal plate.
 8. Themethod according to claim 1, wherein the at least one energy beam is atleast one laser beam and/or at least one electron beam.
 9. The methodaccording to claim 1, wherein the first direction the support structureis rotated is clockwise for a predetermined number of powder layers andanti-clockwise for a predetermined number of powder layers.
 10. Themethod according to claim 1, further comprising the step of preheatingthe powder layer before fusing it.
 11. The method according to claim 10,wherein the preheating is performed by using at least one energy beamsource also used for fusing the powder layer.
 12. The method accordingto claim 10, wherein the preheating is performed by using an energysource not used for fusing the powder layer.
 13. The method according toclaim 10, wherein the preheating is performed during and/or afterapplication of a new powder layer.
 14. A computer program productcomprising at least one non-transitory computer-readable storage mediumhaving computer-readable program code portions embodied therein, thecomputer-readable program code portions comprising one or moreexecutable portions configured for: upon receipt of at least one modelof a three-dimensional article, lowering a support structure apredetermined distance and rotating the support structure apredetermined angle in a first direction before applying a first powderlayer covering the lowered and rotated support structure, rotating thesupport structure the predetermined angle in a second direction oppositeto the first direction before directing the at least one first energybeam from the at least one first energy beam source at selectedlocations for fusing the first powder layer, directing the at least onefirst energy beam from the at least one first energy beam source atselected locations according to the model for fusing the first powderlayer on the support structure, which is stationary, for forming firstportions of the three-dimensional article, and repeating the lowering,rotating, and directing steps until the three-dimensional article isfinished.